TW201707945A - Laminated film and method for producing the same - Google Patents

Abstract

The problem to be addressed in this invention is that the two ends on width direction of the laminated film cannot be employed on polarizing plate due to the color uneven originated from the wrinkles and relaxations. In addition, one more problem to be addressed in this invention is that the polarizing laminated film obtained after dying step cannot be attached with protective film while the wrinkle and relaxation is generated and therefore cannot smoothly producing a polarizing film. The present invention provides a laminated film wherein, wherein the laminated film has a substitutionary non-elongated polyvinylalcohol resin layer on a surface of a rectangular substrate film. While equivalently dividing the polyvinylalcohol resin film into 9 areas on the width direction, the average film thickness of the outset area, D1e, and the average film thickness of the central area, D1c, satisfy the following formula: D1e-D1c ≤ -0.3 [mu]m.

Description

Method for producing laminated film and laminated film

The present invention relates to a method for producing a laminated film and a laminated film.

The conventional polarizer is produced by stretching and dyeing an original sheet film of a polyvinyl alcohol-based resin (generally, having a thickness of about 30 to 75 μm), and the thickness of the film after stretching is usually about 12 to 30 μm. When an original film of a polyvinyl alcohol-based resin is used in an amount of 30 μm or less for film formation, there is a problem in production such as cracking of the film at the time of stretching.

Therefore, in order to cope with the thinning of the polarizing plate of the present day, it has been proposed to apply an aqueous solution containing a polyvinyl alcohol-based resin to the base film. In this embodiment, an aqueous solution containing a polyvinyl alcohol-based resin is applied onto a base film to form a polyvinyl alcohol-based resin layer to obtain a laminated film, and then the laminate film is subjected to stretching and dyeing treatment, thereby imparting A polarizing plate layer is obtained by the polarizing function of a polyvinyl-alcohol-type resin layer (patent document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-098653

When a polarizing laminated film is obtained by applying an aqueous solution containing a polyvinyl alcohol-based resin, the polarizing laminated film can be generally produced by a roll-to-roll method using an elongated base film. In this embodiment, since the steps including the step of stretching the polyvinyl alcohol-based resin layer and the step of dyeing by iodine are repeated, the elongated base material film is wound into a reel shape in each step.

In particular, after the stretching step, the stretched laminated film is wound into a roll shape to obtain an extended laminated film roll, and when the extended laminated film is wound from the extended laminated film roll in order to carry out the dyeing step, the width of the elongated film is rolled. Wrinkles and slacks occur at both ends. After the film is wound into a roll shape, wrinkles and slacks generated at both end portions of the film which are wound out are also generated on the laminated film, and thus wrinkles and slacks are generated to cause color spots in the width direction, and the width direction is The problem of the polarizing plate cannot be used at both ends. In addition, when the polarizing laminated film obtained after the dyeing step is wrinkled or slack, there is a problem that the protective film cannot be bonded and the polarizing plate cannot be stably produced.

The present invention encompasses the invention described below.

[1] A laminated film comprising a laminated film of a substantially unstretched polyvinyl alcohol-based resin layer on at least one surface of the elongated base film, and the polyvinyl alcohol-based resin layer is equally divided into 9 in the width direction. For each region, the average film thickness D1e of the outermost region and the average film thickness D1c of the central region satisfy the following formula: D1e-D1c≦-0.3 μm, wherein the average film thickness D1e of the outermost region is the difference between the average film thickness of each of the outermost two regions and the average film thickness D1c of the central region. Average film thickness.

[2] The laminated film according to the item [1], wherein the average thickness of the polyvinyl alcohol-based resin layer which is not substantially extended in the width direction is 10 μm or less.

[3] An extended laminated film comprising an extended laminated film of an extended polyvinyl alcohol-based resin layer on at least one surface of the elongated base film, wherein the stretched polyvinyl alcohol-based resin layer is in a width direction When the upper portion is divided into nine regions, the average film thickness D2e of the outermost region and the average film thickness D2c of the central region satisfy the following formula: D2e - D2c ≦ 0.25 μm, wherein the average film thickness D2e of the outermost region is set to the most The average film thickness of the difference between the average film thickness of each of the outer two regions and the average film thickness D2c of the central region is larger.

[4] The extended laminated film according to [3], wherein the average thickness of the stretched polyvinyl alcohol-based resin layer in the width direction is 7 μm or less.

[5] The extended laminated film according to [3] or [4], wherein, when the base film is equally divided into nine regions in the width direction, the average film thickness D3e of the outermost region and the average of the central region The film thickness D3c satisfies the following formula: D3e-D3c≦1.0 μm, wherein the average film thickness D3e of the outermost region is the average film thickness D3c of the average film thickness and the central region of each of the outermost two regions. The average film thickness of the larger difference.

[6] The extended laminated film according to any one of [3] to [5] wherein, when the extended laminated film is equally divided into nine regions in the width direction, the average film thickness D4e and the center of the outermost region are The average film thickness D4c of the region satisfies the following formula: D4e-D4c≦1.5 μm, wherein the average film thickness D4e of the outermost region is set as the average of the average film thickness and the central region of each of the outermost two regions. The average film thickness of the difference in film thickness D4c is larger.

[7] A polarizing laminate film comprising a polarizing layer film having a polarizer layer on at least one surface of the elongated base film, and an outermost region when the polarizer layer is equally divided into nine regions in the width direction The average film thickness D5e and the average film thickness D5c of the central region satisfy the following formula: D5e-D5c ≦ 0.25 μm, wherein the average film thickness D5e of the outermost region is set as the average film of each of the outermost two regions. The average film thickness of the difference between the average thickness of the thick medium and the central region D5c is larger.

[8] The polarizing laminated film according to [7], wherein the average thickness of the polarizer layer in the width direction is 7 μm or less.

[9] The polarizing laminate film according to [7], wherein when the base film is equally divided into nine regions in the width direction, the average film thickness D6e of the outermost region and the central region are The average film thickness D6c satisfies the following formula: D6e-D6c≦1.0 μm, wherein the average film thickness D6e of the outermost region is the average film thickness of the average film thickness and the central region of each of the outermost two regions. The average film thickness of the difference between D6c is larger.

[10] The polarizing laminated film according to any one of [7], wherein, when the polarizing laminated film is equally divided into nine regions in the width direction, an average film thickness D7e of the outermost region is obtained. The average film thickness D7c with the central region satisfies the following formula: D7e-D7c≦1.5 μm, wherein the average film thickness D7e of the outermost region is set to be the average film thickness and the central region of each of the outermost two regions. The average film thickness of the difference between the average film thicknesses D7c is larger.

[11] The polarizing laminated film according to any one of [7], wherein the photometric correction monomer transmittance Tye and the position measured at a position of 25 mm from the edge of the polarizing layer in the width direction are The photometric correction monomer transmittance Tyc measured in the center of the width direction of the polarizer layer satisfies the following formula: |Tye-Tyc|≦0.40%, wherein the photometric correction monomer transmittance measured at a position 25 mm from the edge Tye is a photometric corrected monomer transmittance of a difference between the two measured values and the photometric corrected monomer transmittance Tyc measured at the center.

[12] A method for producing a laminated film, comprising: coating a polyvinyl alcohol-based resin on at least one surface of the elongated substrate film so that a central portion in a width direction of the coating layer is thicker than both end portions; An aqueous solution to form a coating layer; and a step of drying the coating layer to form a resin layer containing a polyvinyl alcohol-based resin.

[13] A method for producing an extended laminated film, comprising the step of uniaxially stretching the laminated film according to [12] to more than 5 times to obtain an extended laminated film.

[14] A method of producing an extended laminated film reel comprising the steps of: winding an extended laminated film according to [13] into a roll to obtain an extended laminated film roll.

[15] A method for producing a polarizing laminated film, comprising: dyeing an extended laminated film according to [13] or an extended laminated film obtained by winding an extended laminated film roll according to [14] to obtain polarized light. The step of a laminated film.

[16] A method of producing a polarizing plate, comprising: bonding a protective film to a surface opposite to a side of a substrate film in a polarizing layer of the polarizing laminated film according to the item [15], and obtaining a multilayer film The bonding step is a peeling step of peeling off the base film from the multilayer film.

According to the present invention, it is difficult to cause wrinkles and slack at both end portions in the width direction of the elongated laminated film, and it is possible to reduce the area of a portion which cannot be used as a product. Further, a polarizing plate having uniform optical characteristics in the width direction can be obtained. Further, since the protective film can be easily bonded to the polarizing laminated film, the polarizing plate can be stably produced.

1‧‧‧Base film

2‧‧‧coating layer

3‧‧‧Polyvinyl alcohol resin layer

4‧‧‧Extended polyvinyl alcohol resin layer

5‧‧‧Polarized film

9‧‧‧Substrate film with coating layer

10‧‧‧ laminated film

11‧‧‧Extended laminated film

12‧‧‧Polarized laminated film

30, 32, 34‧‧‧Departs

42‧‧‧Surface activation method

44, 48‧‧‧ Coating method

46, 50‧‧‧ Drying method

52‧‧‧ drive roller

31, 33, 35‧‧ ‧ coiling department

100‧‧‧ outermost area

101‧‧‧Central area

[Fig. 1] A view for explaining a method of producing a laminated film according to an embodiment of the present invention.

[Fig. 2] Fig. 2 is a schematic cross-sectional view showing an example of a base film having a coating layer obtained by an embodiment of the present invention.

[Fig. 3] Fig. 3 is a schematic cross-sectional view showing an example of a laminated film obtained by an embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view showing an example of an extended laminated film obtained by an embodiment of the present invention.

[Fig. 5] Fig. 5 is a schematic cross-sectional view showing an example of a polarizing laminated film obtained by an embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view showing the positions of the outermost region and the central region in the coating layer obtained by an embodiment of the present invention.

[Fig. 7] is a schematic cross-sectional view showing an extended laminated film when the stretched polyvinyl alcohol-based resin layer does not satisfy the requirements of the present invention.

When the polarizer layer is obtained by applying an aqueous solution containing a polyvinyl alcohol-based resin, the polarizing laminated film can be usually produced by a method comprising the following steps.

(Coating Step) A step of applying an aqueous solution containing a polyvinyl alcohol-based resin to at least one surface of the elongated substrate film to obtain a coating layer.

(Drying Step) A step of obtaining a laminated film by forming a polyvinyl alcohol-based resin layer (abbreviated as a resin layer) by drying the coating layer.

(Extension Step) The step of stretching the laminated film to obtain an extended laminated film.

(Dyeing Step) A step of immersing the stretched laminated film in a dyeing solution containing iodine to obtain a polarizing laminated film.

In order to suppress the occurrence of wrinkles and slack at both end portions in the width direction of the polarizing laminated film, the inventors have found that the following intermediate product can be produced in each step of manufacturing the polarizing plate. The length of the intermediate product (the laminated film, the extended laminated film, and the polarizing laminated film) of the present invention in the longitudinal direction can be It is 100m or more, and it can be 500m or more. When the length of the film is 100 m or more, the winding diameter is increased. Therefore, although the winding is likely to occur, the present invention can effectively prevent wrinkles and slack at both end portions in the width direction. Usually the length of the film is 10,000 m or less.

[Intermediate product: laminated film]

In the laminated film including the polyvinyl alcohol-based resin layer on the elongated base film, when the polyvinyl alcohol-based resin layer is equally divided into nine regions in the width direction, the average film thickness D1e and the central region of the outermost region are required. The average film thickness D1c satisfies the following formula (1-1), and it is preferable to satisfy the following formula (1-2). D1e-D1c is preferably -0.4 μm or less, more preferably -1.5 μm or more, and more preferably -1.3 μm or more. Moreover, the average film thickness D1e of the outermost region is the average film thickness of the difference between the average film thickness of each of the outermost two regions and the average film thickness D1c of the central region.

D1e-D1c≦-0.3μm (1-1)

D1e-D1c≧-2.0μm (1-2)

When the laminated film is provided with a polyvinyl alcohol-based resin layer on both surfaces of the base film, the polyvinyl alcohol-based resin layer disposed on at least one surface of the base film satisfies the formula (1-1) and is disposed It is preferable that the polyvinyl alcohol-based resin layer on the surface of the base film satisfies the formula (1-1).

In the film thickness distribution in the width direction of the polyvinyl alcohol-based resin layer, D1e-D1c is an approximate shape indicating the uniformity of the film thickness distribution and the film thickness distribution in the width direction. The polyvinyl alcohol-based resin layer satisfies the formula (1-1), and refers to a polyvinyl alcohol-based resin having a film thickness distribution in a width direction. The layer is disposed on the substrate film. When the film thickness distribution in the width direction is convex, and the laminated film is wound into a reel shape in the winding direction (MD direction) to obtain a laminated film reel, the film thickness distribution in the width direction is In the case of the concave shape, the tension applied to the end portion in the width direction of the laminated film roll can be made small. As a result, both ends in the width direction of the laminated film roll are less likely to be wound up, and it is possible to suppress wrinkles and slack at both end portions in the width direction of the rolled laminated film.

In addition, the laminated film which is wound up by the laminated film roll has wrinkles and slack in the center portion in the width direction, and wrinkles and slack in the center portion in the width direction can be released by the extending step of the subsequent step. On the other hand, wrinkles and slacks generated at both end portions in the width direction are difficult to be released by the stretching step. It is preferable that the polyvinyl alcohol-based resin layer satisfies the formula (1-2) in order to easily remove wrinkles and slack in the central portion in the width direction.

Since the laminated film is a film before the stretching step and the dyeing step, the polyvinyl alcohol-based resin layer is substantially not extended. Substantially unextended, the stretching ratio in the extending direction is 0.99 to 1.01 times.

In the present specification, the width direction means a direction perpendicular to the longitudinal direction of the elongated laminated film and parallel to the laminated film surface. When the laminated film is produced by the reel-to-reel method, the width direction is perpendicular to the transport direction (MD direction) of the laminated film, and coincides with the direction (TD direction) parallel to the laminated film surface. Of course, the length direction is consistent with the MD direction. Further, when the laminated film of the present invention is obtained by extending the laminated film from the stretching step, and further performing the step including the dyeing step to obtain a polarizing laminated film, it is usually extended. The direction is the same as the longitudinal direction of the laminated film, and the absorption axis direction of the polarizing laminated film is aligned with the longitudinal direction of the laminated film. In this relationship, even when the transparent protective film is bonded to the polarizing laminated film, the polarizing plate of the base film is peeled off, and the same is true even when the polarizing plate is cut into a predetermined size.

For example, the laminated film of the present invention has a film thickness distribution in the width direction as shown in Fig. 3 .

[Intermediate product: extended laminated film]

The laminated film is provided with an extended polyvinyl alcohol-based resin layer on at least one surface of the elongated base film. The laminated film may be formed by stretching the laminated film. The stretching ratio of the polyvinyl alcohol-based resin layer may be, for example, 5 to 17 times or 5 to 8 times. When the stretched polyvinyl alcohol-based resin layer is equally divided into nine regions in the width direction, the average film thickness D2e of the outermost region and the average film thickness D2c of the central region must satisfy the following formula (2-1), and satisfy The following formula (2-2) is preferred. D2e-D2c is preferably 0.20 μm or less, more preferably 0.15 μm or less, and more preferably -1.0 μm or more. Moreover, the average film thickness D2e of the outermost region is the average film thickness of the difference between the average film thickness of each of the outermost two regions and the average film thickness D2c of the central region.

D2e-D2c≦0.25μm (2-1)

D2e-D2c≧-1.2μm (2-2)

When the stretched polyvinyl alcohol-based resin layer is provided on both surfaces of the base film, the polyvinyl alcohol-based resin layer disposed on at least one surface of the base film may satisfy the formula (2-1) and be disposed on the base. Any of the faces of the film It is preferable that the polyvinyl alcohol-based resin layer satisfies the formula (2-1).

When the stretched polyvinyl alcohol-based resin layer satisfies the formula (2-1), when the stretched laminated film is wound into an extended laminated film roll, the both ends in the width direction are less likely to occur for the same reason as the laminated film. The winding of the part is suppressed, and the wrinkles and slacks at both ends in the width direction can be suppressed.

In order to more effectively suppress the winding of the stretched laminated film roll, when the base film is equally divided into nine regions in the width direction in the extended laminated film, the average film thickness D3e of the outermost region and the central region are The average film thickness D3c satisfies the following formula (3-1), and it is more preferable to satisfy the following formula (3-2). D3e-D3c is preferably 0.8 μm or less, and more preferably -0.8 μm or more. Further, the average film thickness D3e of the outermost region is the average film thickness of the difference between the average film thickness of each of the outermost two regions and the average film thickness D3c of the central region.

D3e-D3c≦1.0μm (3-1)

D3e-D3c≧-1.0μm (3-2)

The polyvinyl alcohol-based resin layer and the base film are preferably integrally extendable. At this time, the film thickness distribution in the width direction of the base film tends to reflect the film thickness distribution of the stretched polyvinyl alcohol-based resin layer. That is, not only the film thickness distribution in the width direction of the polyvinyl alcohol-based resin layer but also the film thickness distribution in the width direction of the base film can be changed. Therefore, when the film thickness distribution of the stretched polyvinyl alcohol-based resin layer does not satisfy the formula (2-1), for example, as shown in Fig. 7, the stretched polyvinyl alcohol-based resin layer has a concave film thickness distribution. (D2e-D2c>0.25 μm), the film thickness distribution in the width direction of the base film can also be deformed into a concave shape by stretching (D3e-D3c>1.0 μm). On the other hand, this In the extended laminated film of the invention, since the film thickness distribution in the width direction of the stretched polyvinyl alcohol-based resin layer satisfies the formula (2-1) and is approximately smooth, deformation of the base film can be prevented.

Further, when the laminated film is divided into nine regions in the width direction, it is preferable that the average film thickness D4e of the outermost region and the average film thickness D4c of the central region satisfy the following formula (4-1). And to satisfy the following formula (4-2) is better. D4e-D4c is preferably -1.0 μm or more, more preferably 0.0 μm or more, and may be 0.5 μm or more. Moreover, the average film thickness D4e of the outermost region is the average film thickness of the difference between the average film thickness of each of the outermost two regions and the average film thickness D4c of the central region.

D4e-D4c≦1.5μm (4-1)

D4e-D4c≧-2.0μm (4-2)

The thickness of the extended laminated film means the total thickness which is the sum of the thickness of the base film in the extended laminated film and the thickness of the extended resin layer. When the polyvinyl alcohol-based resin layer is provided on one surface of the base film, the total thickness is the sum of the thickness of the base film and the thickness of the polyvinyl alcohol-based resin layer, and when the polyvinyl alcohol-based resin layer is provided on both surfaces of the base film, The thickness is a thickness obtained by adding the thickness of the base film to the sum of the thicknesses of the pair of polyvinyl alcohol-based resin layers. Therefore, when the polyvinyl alcohol-based resin layer is provided on both surfaces of the base film and the formula (4-1) is satisfied, wrinkles and slack at both end portions in the width direction can be more effectively suppressed in the extended laminated film roll.

As described above, the laminated film satisfies the formula (1-1), and the cross-sectional shape in the width direction is convex. The value of the formula (2-1) compared with the value of the formula (1-1) The larger one is considered to be because the end portion of the laminated film having a thin film thickness is thickened by the neck when it is stretched, and the cross-sectional shape in the width direction is changed from a convex shape to a flat shape.

For example, the extended laminated film of the present invention has a film thickness distribution in the width direction as shown in Fig. 4 .

[Intermediate product: polarized laminated film]

The polarizing laminate film is provided with a polarizer layer on at least one surface of the elongated base film. The polarizing laminated film may be obtained by subjecting the extended laminated film to a step including a dyeing step. The polyvinyl alcohol-based resin layer including the step of the dyeing step serves as a polarizer layer. In general, the film thickness distribution in the width direction of each layer (polarizing sheet layer, base film) of the polarizing laminated film is reflected in the width direction of each layer of the extended laminated film.

Therefore, when the polarizer layer is equally divided into nine regions in the width direction as in the case of the extended laminated film, the average film thickness D5e of the outermost region and the average film thickness D5c of the central region must satisfy the following formula (5-1), and It is preferable to satisfy the formula (5-2). D5e-D5c is preferably 0.20 μm or less, more preferably 0.15 μm or less, still more preferably 0.1 μm or less, and most preferably -0.15 μm or more, and more preferably -0.1 μm or more. Moreover, the average film thickness D5e of the outermost region is the average film thickness of the difference between the average film thickness of each of the outermost two regions and the average film thickness D5c of the central region.

D5e-D5c≦0.25μm (5-1)

D5e-D5c≧-2.0μm (5-2)

The polarizing laminated film has a polarizer on both sides of the substrate film In the case of the layer, the polarizer layer disposed on at least one side of the base film satisfies the formula (5-1), and the polarizer layer disposed on the surface of the base film satisfies the formula (5-1). good.

When the polarizing film layer satisfies the formula (5-1) in the width direction, when the polarizing laminated film is wound into a polarizing laminated film reel, it is less likely to cause winding at both end portions in the width direction, and it is possible to suppress the width direction. Wrinkles and slack at both ends.

In order to more effectively suppress the winding of the polarizing laminated film reel, when the base film is equally divided into nine regions in the width direction in the polarizing laminated film, the average film thickness D6e of the outermost region is The average film thickness D6c of the central region satisfies the following formula (6-1), and is more preferable to satisfy the following formula (6-2). D6e-D6c is more preferably 0.9 μm or less, more preferably -1.0 μm or more, and still more preferably -0.8 μm or more. In addition, the average film thickness D6e of the outermost region is the average film thickness of the difference between the average film thickness of each of the outermost two regions and the average film thickness D6c of the central region.

D6e-D6c≦1.0μm (6-1)

D6e-D6c≧-1.5μm (6-2)

In addition, when the polarizing laminated film is divided into nine regions in the width direction, the average film thickness D7e of the outermost region and the average film thickness D7c of the central region satisfy the following formula (7-1). Good, and better to meet the following formula (7-2). D7e-D7c is preferably 1.3 μm or less, more preferably -1.0 μm or more, and more preferably 0 μm or more. In addition, the average film thickness D7e of the outermost region is the flatness of the difference between the average film thickness of each of the outermost two regions and the average film thickness D7c of the central region. The film thickness is uniform.

D7e-D7c≦1.5μm (7-1)

D7e-D7c≧-2.0μm (7-2)

The thickness of the polarizing laminate film refers to the total thickness and is the sum of the thickness of the base film in the polarizing laminate film and the thickness of the polarizer layer. When the polarizer layer is provided on one side of the base film, the total thickness is the sum of the thickness of the base film and the thickness of the polarizer layer. When the polarizer layer is provided on both sides of the base film, the total thickness is the thickness of the base film. The thickness of the sum of the thicknesses of a pair of polarizing sheets is added. Therefore, when the polarizing film layer is provided on both surfaces of the base film and the formula (7-1) is satisfied, wrinkles and slack at both end portions in the width direction can be more effectively suppressed in the polarizing laminated film reel.

Further, in the point of obtaining a polarizing plate having more uniform polarizing properties, the photometric correction unit transmittance Tye and the photometric correction in the center in the width direction measured at a position 25 mm from the edge in the width direction of the polarizing plate layer The monomer permeability Tyc is preferably such that the following formula (8-1) is satisfied. |Tye-Tyc|, preferably 0.3% or less, and more preferably 0.2% or less. |Tye-Tyc| is usually 0.00% or more. Further, the photometric correction unit transmittance Tye measured at a position of 25 mm from the edge is used as a photometric correction unit by the difference between the two measured values and the photometric correction unit transmittance Tyc measured at the center. Transmittance.

|Tye-Tyc|≦0.40% (8-1)

The photometric correction monomer transmittance (Ty) can be obtained by determining the transmittance (T _MD ) in the _MD direction and the transmittance (T _TD ) in the TD direction of the polarizing laminated film at a wavelength of 380 nm to 780 nm. The formula (9) shown below calculates the monomer transmittance in each wavelength, and is obtained by performing photometric correction at a 2 degree angle of view (C light source) of JIS Z 8701.

Monomer penetration rate (%) = (T _MD + T _TD ) / 2 (9)

For example, the polarizing laminate film of the present invention has a film thickness distribution in the width direction as shown in Fig. 5 .

Hereinafter, an embodiment of the method for producing a laminated film of the present invention, a method for producing a polarizing laminated film, and a method for producing a polarizing plate will be described with reference to the drawings.

(Manufacturing method of laminated film)

Fig. 1 is a flow chart showing a method of producing a laminated film according to an embodiment of the present invention.

(substrate film)

First, an elongated base film 1 is prepared. The base film 1 can be formed of a thermoplastic resin. Examples of the thermoplastic resin include a polyolefin resin such as a chain polyolefin resin and a cyclic polyolefin resin (such as a norbornene resin); a polyester resin such as polyethylene terephthalate; and (meth)acrylic acid. Resin; cellulose ester resin such as cellulose triacetate or cellulose diacetate; polycarbonate resin; polyvinyl alcohol resin; polyvinyl acetate resin, polyarylate resin; polyphenylene Ethylene resin; polyether oxime resin; polyfluorene resin; polyamine resin; polyimine resin.

The base film may be a single layer structure formed of one resin layer containing one or two or more thermoplastic resins, or may be included A multilayer structure in which a plurality of resin layers of one or more thermoplastic resins are laminated.

Further, the substrate film may be an extension or an unextended product. In the case of an extension, it may be a uniaxial extension or a biaxial extension.

In addition to a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, a chain polyolefin resin may be a copolymer comprising two or more kinds of chain olefins. It is preferable to use a base film containing a chain olefin-based resin in terms of a point which is easily and stably extended at a high rate. In addition, the base film is made of a polypropylene resin (a polypropylene resin of a homopolymer of propylene, a copolymer mainly composed of propylene, etc.), a polyethylene resin (a polyethylene resin of a homopolymer of ethylene, and ethylene). The copolymer of the main body, etc.) is more preferably.

A copolymer mainly composed of propylene is a copolymer of propylene and another monomer copolymerizable with propylene. Examples of the other monomer copolymerizable with propylene include ethylene and an α-olefin. The α-olefin is preferably an α-olefin having 4 or more carbon atoms, and more preferably an α-olefin having 4 to 10 carbon atoms. Specific examples of the α-olefin having 4 to 10 carbon atoms include linear monoolefins such as 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 1-decene. a branched monoolefin such as 3-methyl-1-butene, 3-methyl-1-pentene or 4-methyl-1-pentene; ethylene cyclohexane or the like. The copolymer of propylene and other monomers copolymerizable with propylene may be a random copolymer or a block copolymer.

In the copolymer, the content of the above other monomer is, for example, 0.1 to 20% by weight, and preferably 0.5 to 10% by weight.

Among the above, polypropylene resin is made by using propylene. A homopolymer, a propylene-ethylene random copolymer, a propylene-1-butene random copolymer or a propylene-ethylene-1-butene random copolymer is preferred.

The cyclic polyolefin resin is a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit, and is a ring-opening (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, a cyclic olefin and ethylene. a copolymer of a chain olefin such as propylene (typically a random copolymer), and a graft polymer modified with the unsaturated carboxylic acid or a derivative thereof, and the like. Among them, a norbornene-based resin having a norbornene-based monomer such as norbornene or a polycyclic norbornene-based monomer as a cyclic olefin is preferably used.

The base film may be composed of one type of cyclic polyolefin resin, or may be composed of a mixture of two or more kinds of cyclic polyolefin resins, or may be composed of a copolymer of two or more kinds of cyclic polyolefin resins.

The polyester resin is a resin having an ester bond, and is generally a polycondensate containing a polyvalent carboxylic acid or a derivative thereof and a polyhydric alcohol. As the polyvalent carboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and examples thereof include terephthalic acid, isophthalic acid, dimethyl terephthalate, and naphthalene dicarboxylic acid. Ester and the like. As the polyhydric alcohol, a divalent diol can be used, and examples thereof include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexane dimethanol.

Specific examples of the polyester resin include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polyparaphenylene. Propylene dicarboxylate, propylene glycol naphthalate, dimethyl dimethyl terephthalate, cyclohexane dimethyl phthalate, and the like. When a polyester resin film such as polyethylene terephthalate is used, it is possible to Extend to increase the modulus of elasticity. The extension may be a uniaxial extension or a biaxial extension.

The base film may be composed of one type of polyester resin, or may be composed of a mixture of two or more kinds of polyester resins, or may be composed of a copolymer of two or more kinds of polyester resins.

Examples of the (meth)acrylic resin include poly(meth)acrylate such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(methyl ) an acrylate copolymer, a methyl methacrylate-acrylate-(meth)acrylic acid copolymer, a methyl (meth)acrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group ( For example, methyl methacrylate methacrylic acid cyclohexyl ester copolymer, methyl methacrylate-(meth)acrylic acid norbornene ester copolymer, etc.). It is preferred to use a poly(meth)acrylic acid C _1-6 alkyl ester such as poly(methyl) acrylate, and to use methyl methacrylate as a main component (50 to 100% by weight, and 70 to 100 A methyl methacrylate-based resin having a % by weight is more preferable.

The base film may be composed of one type of (meth)acrylic resin, or may be composed of a mixture of two or more kinds of (meth)acrylic resins, or may be composed of a copolymer of two or more kinds of (meth)acrylic resins. .

A cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Among these resins, cellulose triacetate (cellulose triacetate) is particularly preferred.

The base film may be composed of one type of cellulose ester resin, or may be composed of a mixture of two or more kinds of cellulose ester resins, or may be composed of a copolymer of two or more kinds of cellulose ester resins.

The polycarbonate resin is a polymer containing a monomer unit bonded via a carbonate group. The polycarbonate resin may be a resin called modified polycarbonate or a modified wavelength-dependent copolymerized polycarbonate which has a polymer skeleton modified to lower the photoelastic coefficient.

The base film may be composed of one type of polycarbonate resin, or may be composed of a mixture of two or more kinds of polycarbonate resins, or may be composed of a copolymer of two or more kinds of polycarbonate resins.

In the base film, any appropriate additive may be added in addition to the above thermoplastic resin. Examples of such an additive include an ultraviolet absorber, an antioxidant, a smoothing agent, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the substrate film is preferably from 50 to 100% by weight, more preferably from 50 to 99% by weight, still more preferably from 60 to 98% by weight, still more preferably from 70 to 97% by weight. When the content of the thermoplastic resin in the base film is less than 50% by weight, the high transparency and the like which the thermoplastic resin originally has cannot be sufficiently exhibited.

The thickness of the base film 1 can be appropriately determined, but it is preferably from 1 to 500 μm, more preferably from 1 to 300 μm, and from 5 to 200 μm in terms of operability such as strength and handleability. More preferably, it is preferably 5 to 150 μm.

The width of the base film 1 can be appropriately determined, and it may be 500 mm or more, or may be 1,000 mm or more. In the laminated film of the present invention, even if the width is 500 mm or more, wrinkles and slack at both end portions in the width direction can be effectively suppressed. Moreover, the length of the base film 1 is longer than the width. Yes, it may be 100 m or more, and 500 m or more is suitable.

From the viewpoint of suppressing defects such as wrinkles and wrinkles in the drying step and drying defects of the coating layer, the tensile modulus of the base film at 80 ° C may be 140 MPa or more, preferably 180 MPa or more, and more preferably 200 MPa or more. Better. Further, in general, the tensile modulus of the base film at 80 ° C is 1,000 MPa or less, preferably 800 MPa or less, more preferably 600 MPa or less. If the tensile modulus of the base film at 80 ° C exceeds 1,000 MPa, the apparatus becomes enormous because of the large force required in the stretching step.

(Pretreatment of substrate film)

In order to improve the adhesion to the polyvinyl alcohol-based resin layer, pretreatment may be performed on the surface of the base film 1 by a pretreatment method as needed.

(surface activation)

For example, as shown in Fig. 1(a), on the surface of the substrate film 1 supplied from the winding portion 30, the substrate film 1 can be subjected to a surface activation mode 42 such as corona treatment, plasma treatment or flame treatment. Surface activation treatment.

(former layer formation)

Further, in order to improve the adhesion to the polyvinyl alcohol-based resin layer, the primer layer may be formed on the surface of the base film 1 by a primer layer formation method, preferably by forming a primer layer. A lacquer layer is formed on the surface subjected to the above surface activation treatment.

For example, as shown in FIG. 1(b), by coating method 44 After the coating liquid for forming a primer layer is applied onto the surface of the substrate film 1 which can be supplied from the winding portion 32, the coating layer is dried by the drying method 46 to obtain a substrate film having a primer layer, and then The base film 1 can be taken up by the take-up portion 33. The coating liquid for forming a primer layer may contain a resin component and a solvent. The resin component is preferably a thermoplastic resin which is excellent in transparency, heat stability, and elongation, and examples thereof include a (meth)acrylic resin and a polyvinyl alcohol resin. As the solvent, a general organic solvent capable of dissolving the above resin component and an aqueous solvent such as water can be usually used.

It is also possible to add a crosslinking agent to the coating liquid for forming a primer layer to increase the strength of the primer layer. The crosslinking agent may be appropriately selected from known ones such as an organic system and an inorganic system depending on the type of the thermoplastic resin to be used. For the crosslinking agent, a crosslinking agent described in WO2013/146644 can be used. The primer layer coating liquid preferably has a solid content concentration of about 1 to 25% by weight.

The thickness of the primer layer is preferably from 0.05 to 1 μm, more preferably from 0.1 to 0.4 μm.

An example of the coating method 44 of applying the coating liquid for forming a primer layer to the base film 1 may be the same as or different from the coating method 48 for forming a polyvinyl alcohol-based resin layer to be described later.

(Application of polyvinyl alcohol resin solution)

After the pre-treatment, as shown in FIG. 1( c ), for example, a solution of a polyvinyl alcohol-based resin is applied onto the surface of the base film 1 supplied from the take-up portion 34 by a coating method 48 to form a coating layer 2 . . a solution of a polyvinyl alcohol resin, The powder of the polyvinyl alcohol-based resin is obtained by dissolving in a water-based solvent such as water.

Examples of the polyvinyl alcohol-based resin include a polyvinyl alcohol resin and a derivative thereof. Examples of derivatives of polyvinyl alcohol resins include polyethylene formaldehyde; polyvinyl acetal; polyvinyl alcohol resins such as olefins such as ethylene and propylene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; and unsaturated carboxylic acids. Alkyl ester, acrylamide and other modified people.

The average degree of polymerization of the polyvinyl alcohol-based resin is preferably from 100 to 10,000, more preferably from 1,000 to 10,000. Especially better from 1,500 to 8,000, and best from 2,000 to 5,000. The average degree of polymerization is a value obtained by the method specified in JIS K 6726 (1994). If the average degree of polymerization is less than 100, it is difficult to obtain good optical characteristics. When it exceeds 10,000, the solubility in water will deteriorate and it will become difficult to form a resin layer.

The polyvinyl alcohol-based resin is preferably a saponified product. The degree of saponification is preferably from 80.0 to 100.0 mol%, more preferably from 90.0 to 99.5 mol%, and still more preferably from 93.0 to 99.5 mol%. For example, a polyvinyl alcohol-based resin having a degree of saponification of 98.0 to 99.5 mol% can be used.

When the degree of saponification is less than 80.0 mol%, it is difficult to obtain good optical characteristics. The degree of saponification is defined by the following formula, in which the proportion of the acetic acid group contained in the polyvinyl acetate-based resin of the raw material of the polyvinyl alcohol-based resin is converted into a hydroxyl group by a saponification step, expressed as a unit ratio (% by mole). Value: degree of saponification (% by mole) = (number of hydroxyl groups) / (number of hydroxyl groups + number of acetate groups) × 100, which can be determined by a method specified in JIS K 6726 (1994).

The solid concentration in the solution is preferably 5% by weight or more, more preferably 5 to 15% by weight, still more preferably 5 to 10% by weight. If it is less than 5% by weight, the amount of water will increase and the drying efficiency will deteriorate. When it exceeds 15% by weight, the viscosity tends to increase and handling tends to be difficult.

The viscosity of the solution at the time of coating is preferably 500 to 10,000 cps, more preferably 1,000 to 7,000 cps, and still more preferably 1,000 to 5,000 cps. If the viscosity is less than 500 cps, it tends to be difficult to regulate the film thickness. If it exceeds 10,000 cps, the liquid supply tends to be difficult. Further, the viscosity of the solution may be adjusted by heating or cooling the solution in addition to the composition of the solution.

Examples of the aqueous solvent include alcohols such as water and methanol.

The solution may also contain additives such as a plasticizer or a surfactant as needed. As the plasticizer, a polyhydric alcohol or a condensate thereof or the like can be used, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the additive to be added is suitably 20% by weight or less based on the polyvinyl alcohol-based resin.

For the coating method 48, a roll coating method such as a bar coating method, a reverse coating method, or a concave coating method; a die coating method; a comma coating method; and a lip coating method can be appropriately selected ( Lip coating method; spin coating method; knife coating method; screen coating method; fountain coating method; dip coating method; spray coating method. In the coating step of the polyvinyl alcohol-based resin solution, the substrate film 1 is continuously applied while being transported to the longitudinal direction thereof. The length direction may not necessarily be the horizontal direction. It is preferable to apply it on the upper surface of the base film 1.

The average film thickness (WET film thickness) of the solution of the applied polyvinyl alcohol-based resin can be, for example, 50 to 200 μm. Solution coating width The degree may be the same as the total width of the substrate film 1, but may be narrower than the total width of the substrate film 1.

As shown in Fig. 2(a), in the present invention, a solution of a polyvinyl alcohol-based resin is applied so that a central portion of the coating layer 2 in the width direction is thicker than both end portions, thereby forming a coating layer 2. . In such a coating method, for example, in the gravure coating method, a blade having a sharp-pointed shape is used, and the amount of the scraping solution is reduced to a central portion and a large number of both end portions are used. In the coating method, the interval between the slit for discharging the coating liquid and the liquid retaining portion formed between the leading edge and the blade edge is a method in which the center portion is wide and both end portions are narrow; in the knife coating method, A method in which a blade-shaped curved blade is used so that the distance between the base film and the blade edge is wide at the center portion and narrow at both end portions; in the comma coating method, the film body of the film is wound around the support At both ends of the backup roll, the distance between the comma roll and the base film is made wide at the center portion and narrow at both ends.

In the coating layer 2 (layer before drying to obtain a polyvinyl alcohol-based resin layer), the film thickness measured in the center in the width direction and the film measured at a position 50 mm from the edge in the width direction of the coating layer. The thickness comparison is preferably a thick coating of 2.5% or more, and a thick coating of 3.0% or more is more preferable.

Usually, a thick coating of about 5.0% is sufficient. Further, the film thickness measured at a position of 50 mm from the edge was defined as the film thickness between the two measured values and the film thickness measured at the center.

The coating layer 2 is obtained by coating the polyvinyl alcohol-based resin solution in this manner, and the coating layer 2 is dried to form the above formula (1-1). Polyvinyl alcohol-based resin layer 3.

(drying step)

Next, while the base film 1 of the applied solution is conveyed in the longitudinal direction, the applied solution is dried by the drying method 50, and as shown in Fig. 3(a), the substrate film 1 is obtained. The laminated film 10 of the present invention of the polyvinyl alcohol-based resin layer 3.

In the drying step, the conveyance direction of the base film 1 is preferably in the horizontal direction, but it may be conveyed in a direction inclined with respect to the horizontal direction as long as it is about 45 degrees with respect to the horizontal system.

In the example of the drying method 50, a floating dryer which supports the substrate film 1 in the air by supplying hot air on both sides of the substrate film without contact, and drying the substrate film 1 is irradiated with infrared rays to the substrate film 1 which can be transported in the air. Infrared dryer, microwave dryer.

The drying temperature, for example, the temperature of the resin layer at the time of drying, or the hot air temperature at the time of supplying hot air to the substrate film 1, can be, for example, 50 to 200 ° C, preferably 60 to 150 ° C, and more preferably 80 ° C or higher. good. When the solution contains water, it is preferred to set the temperature to 80 ° C or higher. The drying time, that is, the running time of transporting the film in a dry mode can be set to 2 to 20 minutes. Further, in the drying step, it is preferred to apply a solution on the surface of the substrate film 1.

By this drying step, as shown in Fig. 3(a), the laminated film 10 having the polyvinyl alcohol-based resin layer 3 on one surface of the base film 1 can be formed. In terms of good polarizing performance and durability, after drying The average value of the thickness of the polyvinyl alcohol-based resin layer 3 is usually 20 μm or less, and preferably 10 μm or less. Further, the average value of the thickness of the polyvinyl alcohol-based resin layer 3 is usually 2 μm or more.

Further, the surface pre-treatment, the solution coating, and the drying step of the substrate film 1 as described above may be performed again on the opposite side of the substrate film, as shown in FIG. 3(b), or in the substrate. A laminated film 10 having a polyvinyl alcohol-based resin layer 3 is formed on both surfaces of the film 1.

Further, pretreatment and application of the solution may be performed on both surfaces of the base film 1, and the coating layers provided on both surfaces of the base film 1 may be simultaneously dried.

Further, in the above embodiment, the steps of pre-treatment, formation of a primer layer, and formation (coating and drying) of a resin layer are performed in batches, that is, in each step. The reel of the film is obtained, and the film is wound out from the reel in the next step and processed. However, any two or more steps in the steps may be continuously performed, that is, not wound into a reel. Two or more steps are continuously performed.

(Manufacturing method of extended laminated film)

Then, the laminated film 10 obtained is wound up from the film roll (the polyvinyl alcohol-based resin layer 3 may be provided only on one surface of the base film 1, and the polyvinyl alcohol-based resin layer 3 may be provided on both surfaces of the base film 1). The extension was carried out to obtain an extended laminated film of the present invention. Further, the dyeing step may be performed before the stretching step, or the stretching step and the dyeing step may be simultaneously performed. Moreover, it can be extended in the air or extended in water. Preferably, the stretched laminated film is wound into a roll to obtain an extended laminated film roll. The storage period of the extended laminated film reel is 2 years. It is better inside, and it is better within one year. When the transport time of the reel from the extension step to the next step is also regarded as the storage period, the normal storage period is 30 minutes or longer. In order to prevent warpage and deterioration of the surface state due to the movement of moisture, it is preferable to use a moisture-proof countermeasure such as covering an extended laminated film reel with an aluminum retort film.

After the end of each step, the film is temporarily formed into a reel shape, whereby the loss at the time of occurrence of a problem or the start-up step in any step becomes smaller than the loss at the time of continuously performing each step. The storage of the reels other than the extended laminated film reel may be the same as described above.

For extension, various methods known in the art can also be used. For example, it may extend in the longitudinal direction extending in the longitudinal direction of the laminated film 10, or may extend in the lateral direction extending in the width direction of the laminated film 10, or may extend obliquely. Among them, it is preferable to extend the longitudinal direction (uniaxial) while carrying the laminated film 10 in the longitudinal direction. The stretching ratio can be appropriately adjusted depending on the required polarizing characteristics, and can be, for example, 5 to 17 times and 5 to 8 times.

Extension can be carried out in one stage or in multiple stages.

In the stretching step, it is preferred that the base film also extends integrally with the elongation of the polyvinyl alcohol-based resin layer. In other words, it is preferable that the stretching ratio of the polyvinyl alcohol-based resin layer is substantially the same as the stretching ratio of the base film. The stretching ratio is substantially the same, and means that the difference between the stretching ratio of the polyvinyl alcohol-based resin layer and the stretching ratio of the base film is 0, and the difference is preferably 0.0. Moreover, the extension of the polyvinyl alcohol-based resin layer The direction of extension to the substrate film is preferably substantially the same. The direction in which the extending direction is substantially the same means that the angle between the extending direction of the polyvinyl alcohol-based resin layer and the extending direction of the substrate film is less than 5°, and the angle formed is preferably less than 1°.

The average value of the thickness of the stretched polyvinyl alcohol-based resin layer in the width direction is preferably 10 μm or less, more preferably 7 μm or less, and still more preferably 5.5 μm or less. In addition, the average value of the thickness in the width direction of the stretched polyvinyl alcohol-based resin layer is usually 1 μm or more, and preferably 2 μm or more, in terms of imparting good durability.

(Method for producing polarizing laminated film)

In the dyeing step, various methods known in which a laminate film or an extended laminate film is immersed in a dyeing tank can be utilized. For example, a dichroic dye can be used as the dye. Examples of dichroic pigments include iodine and organic dyes. In the dyeing, the cross-linking treatment of polyvinyl alcohol can also be carried out in a resin tank. After dyeing, it is preferred to wash and dry the laminated film.

The average value of the thickness of the polarizer layer is preferably 10 μm or less, more preferably 7 μm or less, and still more preferably 5.5 μm or less. In general, the average thickness of the polarizer layer is usually 1 μm or more, and preferably 2 μm or more.

(Method of manufacturing polarizing plate)

Next, a method of manufacturing the polarizing plate will be described. First, a protective film is adhered to the polarizer layer 5 of the polarizing laminate film 12 via an adhesive to obtain a multilayer. membrane. When the polarizer layer 5 is provided on both surfaces of the base film 1, the protective film is adhered to each of the polarizer layers 5. Next, the base film 1 is peeled off from the multilayer film to obtain two polarizing plates in which the protective film is bonded to the polarizer layer 5 via an adhesive. When the polarizing laminate film 12 has the polarizer layer 5 on only one side, one polarizing plate can be obtained.

In the present invention, since the slack and wrinkles at both end portions in the width direction of the polarizing laminated film can be suppressed, when the protective film is bonded to the polarizing plate layer, the polarizing plate can be manufactured with high yield and stability.

As the protective film 3, various known films can be used. For example, a film exemplified as the base film 1 can be used.

As the subsequent agent, various known adhesives can be used. For example, an active energy ray-curable adhesive such as an ultraviolet curable epoxy resin can be used.

The obtained polarizing plate can be taken up and stored on a shaft as a polarizing plate reel. In the polarizing plate of the present embodiment, since the thickness of the end portion in the width direction of the polarizing plate layer 5 is not too thick compared with the thickness of the central portion in the width direction of the polarizing plate layer 5, the polarizing plate is stored as a reel. At the same time, the same effect of preventing slack as described above can be exerted. The polarizing plate is taken out from the stored reel as needed, and cut to a desired size. The obtained polarizing plate can be made thinner, and can be suitably used as a polarizing material such as a liquid crystal display element, and can be incorporated into a liquid crystal display.

[Examples]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples. In the example, except Unless otherwise stated, it indicates the amount of use and the amount of the content and the basis weight basis.

[Measurement of film thickness of coating layer]

The thickness of the coating layer was measured at a position of 50 mm from the edge in the width direction of the coating layer and a position at the center by a film thickness measuring machine (SI-80T) manufactured by Keyence Co., Ltd. The film thickness of the coating layer was measured at intervals of 7 mm in the MD direction on an inline, and the film thickness data of 10 m (m) was averaged.

[Other film thickness measurement]

The film thickness across the entire width direction was measured by an interference type film thickness meter (F20) manufactured by Filmetrics. The sample was measured while moving the sample by the automatic stage so that the film thickness data was acquired at an interval of 2 mm or less.

[Example 1] <Production of laminated film> (1) Substrate film

An unstretched polypropylene (PP) film (melting point: 163 ° C) having a thickness of 90 μm was prepared as a substrate film. The tensile modulus of this base film at 80 ° C was 205 MPa.

(2) Modulation of coating liquid

Polyvinyl alcohol resin powder ("Z-200" manufactured by Nippon Synthetic Chemical Co., Ltd., average polymerization degree 1,100, average saponification degree: 99.5 mol%) was dissolved in hot water at 95 ° C to prepare a concentration of 3% by weight. Polyethylene An aqueous alcohol solution. In the obtained aqueous solution, 1 part by weight of a crosslinking agent ("SUMIREZ RESIN (registered trademark) 650" manufactured by Sumitomo Chemical Co., Ltd.) was added to 2 parts by weight of the polyvinyl alcohol resin powder to obtain a coating for forming a primer layer. Cloth liquid.

Further, polyvinyl alcohol resin powder ("PVA124" manufactured by Kuraray Co., Ltd., average polymerization degree 2400, average saponification degree: 98.0 to 99.0 mol%) was dissolved in hot water at 95 ° C to prepare a polycondensate having a concentration of 8 wt%. A coating liquid for forming a resin layer of a vinyl alcohol aqueous solution.

(3) Coating and drying ‧ single-area layer

A corona treatment was applied to one surface of the substrate film while continuously conveying the substrate film. The coating liquid for forming a primer layer was continuously applied onto the corona-treated surface of the substrate film by a dica coating machine, and dried at 60 ° C for 3 minutes to form a primer layer having a thickness of 0.2 μm. . Then, the coating liquid for forming a resin layer was continuously applied onto the primer layer by a comma coating method while conveying the substrate film to obtain a coating layer. By winding a polyethylene terephthalate film having a thickness of 20 μm around both end portions of the support roll, the distance between the comma-type wiper roll and the base film is wide at the center portion and narrow at both end portions. The coating layer was dried at 80 ° C for 10 minutes in a drying oven to form a polyvinyl alcohol (PVA)-based resin layer having an average thickness of 9.7 μm in the width direction on the primer layer.

At this time, in the thickness distribution (WET film thickness) of the coating layer in the width direction, the center is about 3.5% thicker than the both end portions (the position at a distance of 50 mm from the edge). Further, in the film thickness distribution in the width direction of the resin layer, D1e-D1c= -0.54 μm.

‧ two-layer layer

Further, the same treatment as in the case of producing the above-described single-area layer is applied to the surface (second coating surface) on the opposite side to the surface (first coating surface) on which the above-mentioned resin layer is formed on the base film, and the thickness is 0.2. The primer layer of μm and the polyvinyl alcohol-based resin layer having an average thickness of 9.6 μm in the width direction were formed into a two-layer layer. Then, the laminated film (two-area layer) was taken up in a roll shape to obtain a laminated film roll.

At this time, in the thickness distribution (WET film thickness) of the coating layer on the second coated surface in the width direction, the central portion was thicker by about 3.0% than the both end portions (the position of 50 mm from the edge). Further, in the film thickness distribution in the width direction of the resin layer, D1e - D1c = -0.40 μm.

<Production of extended laminated film> (4) Extension

When the laminated film (two-area layer) is taken up from the laminated film roll obtained in the above (3) and continuously conveyed, the roll extends between the rolls at a stretching temperature of 140 ° C in the longitudinal direction (MD direction) to 2.5 times, and then The elongation temperature was 160 ° C and extended in the longitudinal direction to a total stretching ratio of 5.8 times to prepare an extended laminated film. Further, the stretched laminated film was taken up in a roll shape to obtain an extended laminated film roll. When the laminated film was rolled up, wrinkles and slack were not observed at both end portions in the width direction of the laminated film, and slack was observed in the center portion in the width direction. However, in the extended laminated film, it is not confirmed at the end/center portion in the width direction at the same time. To wrinkles, slack.

The average thickness in the width direction of the resin layer on the first coated surface and the second coated surface in the extended laminated film was 4.9 μm and 4.9 μm, respectively. At this time, in the film thickness distribution in the width direction of the stretched polyvinyl alcohol-based resin layer on the first coated surface and the second coated surface, D2e-D2c = 0.07 μm and 0.11 μm, respectively. When the two resin layers provided in the extended laminated film were peeled off and the base film was taken out, D3e-D3c was 0.73 μm in the film thickness distribution in the width direction of the base film. In the film thickness distribution in which the total thickness in the width direction of the laminated film was extended, D4e-D4c = 1.48 μm.

<Production of polarizing laminated film> (5) Dyeing/crosslinking

The extended laminated film obtained from the above (4) is taken up by the extended laminated film, and the extended laminated film is immersed in a dyeing solution containing 30% of iodine and potassium iodide in a soaking time of about 150 seconds to dye the resin layer. The treatment was followed by rinsing the excess dye solution with pure water at 10 °C. Next, the stretched laminated film was immersed in a crosslinking solution containing boric acid and potassium iodide at 76 ° C for a residence time of 600 seconds, and subjected to crosslinking treatment to obtain a polarizing laminated film. Then, the polarizing laminated film was washed with pure water at 10 ° C for 4 seconds, and dried at 80 ° C for 300 seconds. Further, the polarizing laminated film was taken up to prepare a polarizing laminated film reel. Further, when the stretched laminated film was rolled out, wrinkles and slack were not observed at both end portions and the central portion.

The average thickness in the width direction of the polarizer layer on the first coated surface and the second coated surface in the polarizing laminated film is 5.8, respectively. Mm and 5.8μm. At this time, the film thickness distribution in the width direction of the polarizer layer on the first coated surface and the second coated surface was D5e-D5c=−0.12 μm and −0.09 μm, respectively. When the two polarizer layers provided in the polarizing laminate film were peeled off and the base film was taken out, D6e-D6c was 0.91 μm in the film thickness distribution in the width direction of the base film. In the film thickness distribution of the total thickness in the width direction of the polarizing laminated film, D7e-D7c = 1.21 μm.

The polarizer layer on the second coated surface side was peeled off and removed to prepare a polarizing laminated film including two layers of the polarizer layer on the substrate/first coated surface side. Samples were prepared by cutting both end portions and the center portion of the polarizing laminated film.

The photometric corrected monomer transmittance Ty of the sample having the polarizer layer on the first coated surface side was measured by an integrating sphere spectrophotometer (manufactured by JASCO Corporation, V7100). The incident light is incident from the side of the polarizing sheet. The photometric correction monomer transmittance Tye is 42.51% in the Ty at both end portions of the polarizer layer on the first coated surface side, and the difference in the photometric correction monomer transmittance Tyc from the central portion is larger. At this time, the degree of polarization Py is 99.983%. The central part of Tyc is 42.34%, and the degree of polarization Py is 99.978%.

Further, Ty was also measured in the same manner for the polarizer layer on the second coated surface side which had been removed. The photometric correction monomer transmittance Tye of the two ends of the polarizer layer on the second coating surface side is larger than the photometric correction monomer transmittance Tyc of the central portion. At this time, the degree of polarization Py is 99.980%. The central part of Tyc is 42.52%, and the degree of polarization Py is 99.981%.

Therefore, the value of |Tye-Tyc| is on the side of the first coated side The polarizer layer was 0.17%, and the polarizer layer on the second coated side was 0.07%.

<Production of polarizing plate> (6) Adjustment of the adhesive solution

Polyvinyl alcohol resin powder ("KL-318" manufactured by Kuraray Co., Ltd., average polymerization degree: 1,800) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3 wt%. In the obtained aqueous solution, 1 part by weight of a crosslinking agent ("SUMIREZ RESIN (registered trademark) 650" manufactured by Sumitomo Chemical Co., Ltd.) was mixed with 2 parts by weight of the polyvinyl alcohol resin powder to prepare an adhesive solution.

The polarizing laminated film obtained in the above (5) is taken up by a polarizing laminated film, and after applying the above-mentioned adhesive solution to both of the polarizing sub-layers, a saponified protective film is applied to the bonding surface. A transparent protective film of cellulose triacetate (TAC) ("KC4UY" manufactured by Konica Minolta Co., Ltd.) having a thickness of 40 μm was bonded to the respective polarizer layers. The polarizer layer and the TAC film are pressure-bonded by passing between a pair of bonding rolls to obtain a TAC film/polarizing sheet/primer layer/substrate film/primer layer/polarizing sheet/TAC film. Fit the film. When the polarizing laminated film was taken out, wrinkles and slack were not observed at both end portions and the central portion.

The adhesive film is peeled off from between the base film and the primer layer, and the bonded film is divided into two films: a film having a TAC film/polarized sheet/primer layer/base film in sequence. And a film having a primer layer/polarizing sheet/TAC film in sequence. Next, the base film is peeled off and removed to obtain A sequential polarizing plate having a TAC film/polarizing sheet/primer layer is sequentially ordered. In the peeling step, defects such as cracking of the original film are not produced.

[Embodiment 2]

Except that the substrate film in Example 1 was changed to a polyethylene terephthalate (PET) film having a thickness of 38 μm, and a primer layer was not formed on the substrate film, the same operation was performed on one side. Laminated material. The average thickness of the polyvinyl alcohol-based resin layer in the width direction was 9.5 μm. At this time, in the thickness distribution (WET film thickness) of the coating layer in the width direction, the center was about 3.3% thicker than both end portions (positions at a distance of 50 mm from the edge). Further, in the film thickness distribution in the width direction of the resin layer, D1e - D1c = -0.32 μm.

The laminated film roll is taken up to the laminated film roll, and then the laminated film is taken up from the laminated film roll. At this time, wrinkles and slack were not observed at both end portions in the width direction of the laminated film, and slack was observed in the central portion in the width direction.

[Comparative Example 1] ‧ single-area layer

A single-area layer was produced in the same manner as in Example 1 except that the film thickness distribution (WET film thickness) of the coating layer was not particularly controlled. At this time, the film thickness of the coating layer is almost flat in the width direction. The average thickness of the polyvinyl alcohol-based resin layer in the width direction was 9.7 μm. At this time, in the film thickness distribution in the width direction of the resin layer, D1e - D1c = 0.68 μm.

‧ two-layer layer

In addition, the film thickness distribution (WET film thickness) of the coating layer is not particularly performed on the surface (second coating surface) opposite to the surface (first coating surface) on which the resin layer is formed in the base film. In addition to the control of the above, the resin layer was formed in the same manner as in Example 1 to produce a laminated film (two-area layer). Then, the laminated film was taken up to obtain a laminated film reel. At this time, the average thickness of the polyvinyl alcohol-based resin layer on the second coated surface in the width direction was 9.8 μm. Further, in the film thickness distribution in the width direction of the resin layer, D1e - D1c = 0.64 μm.

The same operation as in Example 1 was carried out, and the laminated film was stretched to produce an extended laminated film. And the stretched laminated film is taken up to obtain an extended laminated film reel. Further, when the laminated film was wound up, slack was confirmed only at both end portions of the laminated film.

The average thickness in the width direction of the resin layer on the first coated surface and the second coated surface in the extended laminated film was 4.8 μm and 4.8 μm, respectively. At this time, the film thickness distribution in the width direction of the resin layer on the first coated surface and the second coated surface was D2e-D2c=0.28 μm and 0.37 μm, respectively. When the two resin layers provided in the extended laminated film were peeled off and the base film was taken out, D3e-D3c was 1.47 μm in the film thickness distribution in the width direction of the base film. In the film thickness distribution in which the total thickness of the laminated film in the width direction is extended, D4e-D4c = 2.28 μm.

Next, the same operation was carried out except that the residence time of the extended laminated film in Example 1 in the dyeing solution was about 170 seconds, and the stretched laminated film was taken up from the stretched laminated film roll to carry out the dyeing step and crosslinking. The step of producing a polarizing laminated film. Then, the polarizing laminated film was taken up to obtain a polarizing laminated film reel. Also, when the extended laminated film is rolled out, Slack was confirmed only at both end portions of the extended laminated film. The average thickness in the width direction of the polarizer layer on the first coated surface and the second coated surface in the polarizing laminated film was 5.9 μm and 5.9 μm, respectively.

At this time, in the film thickness distribution in the width direction of the polarizer layer on the first coated surface and the second coated surface, D5e-D5c = 0.27 μm and 0.28 μm, respectively. When the two polarizer layers provided in the polarizing extension laminated film were peeled off and the base film was taken out, D6e-D6c=1.3 μm in the film thickness distribution in the width direction of the base film. In the film thickness distribution of the total thickness in the width direction of the polarizing laminated film, D7e-D7c = 2.11 μm.

The polarizer layer on the second coated surface side was peeled off and removed, and a polarizing laminated film including two layers of the polarizer layer on the substrate/first coated surface side was produced. Samples were prepared by cutting both end portions and the center portion of the polarizing laminated film.

The same operation as in Example 1 was carried out, and Ty of the sample having the polarizing plate layer on the first coated surface side was measured.

In the Ty of both end portions of the polarizer layer on the first coated surface side, the difference from the central portion of Tyc is 41.52%, and the degree of polarization Py is 99.997%. The central part of Tyc is 41.10% and the degree of polarization Py is 99.998%.

Further, the same measurement Ty as in Example 1 was also performed on the removed polarizer layer on the second coated surface side.

In the Ty of the polarizing plate layer on the second coating surface side, the difference between Ty and the central portion of Ty is 41.42%, and the degree of polarization Py is 99.998%. The Tyc in the central part is 40.94%, and the polarization Py is 99.998%.

Therefore, the value of |Tye-Tyc| is 0.42% in the polarizer layer on the first coated surface side and 0.48% in the polarizer layer on the second coated surface side.

When the polarizing laminated film was wound out from the polarizing laminated film roll, it was confirmed that the both ends in the width direction were slack. When the adhesive solution is applied to the two polarizer layers in the polarizing laminate film and the protective film is bonded, the slack portion becomes wrinkles and the protective film is not bonded.

The results of Examples 1 and 2 and Comparative Example 1 are shown in Tables 1 to 3. Also, the units of numerical values in the tables are μm unless otherwise stated. Therefore, in the stretching step and the dyeing step of the present invention, the both end portions in the width direction are suppressed from being slack, and the polarizing plate can be stably produced, and the optical characteristics in the width direction are uniform.

[Industrial availability]

According to the present invention, it is difficult to cause wrinkles and slack at both end portions in the width direction of the elongated laminated film, and it is possible to reduce the portion which cannot be used as a product. The area of the division. Further, a polarizing plate having uniform optical characteristics in the width direction can be obtained. Further, the protective film can be easily bonded to the polarizing laminated film, and the polarizing plate can be stably produced.

1‧‧‧Base film

10‧‧‧ laminated film

30, 32, 34‧‧‧Departs

31, 33, 35‧‧ ‧ coiling department

42‧‧‧Surface activation method

44, 48‧‧‧ Coating method

46, 50‧‧‧ Drying method

52‧‧‧ drive roller

Claims (16)

A laminated film comprising a laminated film of a substantially unstretched polyvinyl alcohol-based resin layer on at least one surface of the elongated base film, and when the polyvinyl alcohol-based resin layer is equally divided into nine regions in the width direction The average film thickness D1e of the outermost region and the average film thickness D1c of the central region satisfy the following formula: D1e-D1c≦-0.3 μm, wherein the average film thickness D1e of the outermost region is set to be the outermost two regions. The average film thickness of the difference between the average film thickness of the average film thickness and the average film thickness D1c of the central region is larger. The laminated film according to the first aspect of the invention, wherein the average thickness of the polyvinyl alcohol-based resin layer which is not substantially extended in the width direction is 10 μm or less. An extended laminated film comprising an extended laminated film of an extended polyvinyl alcohol-based resin layer on at least one surface of an elongated base film, and the above-mentioned stretched polyvinyl alcohol-based resin layer is equally divided into 9 in the width direction In the case of the regions, the average film thickness D2e of the outermost region and the average film thickness D2c of the central region satisfy the following formula: D2e-D2c ≦ 0.25 μm, wherein the average film thickness D2e of the outermost region is set to be the outermost two regions. The average film thickness of the average film thickness of each of them is larger than the average film thickness D2c of the central region. The extended laminated film according to the third aspect of the invention, wherein the average thickness of the stretched polyvinyl alcohol-based resin layer in the width direction is 7 μm or less. The extended laminated film according to Item 3 or 4, wherein the average film thickness D3e of the outermost region and the average film of the central region when the base film is equally divided into nine regions in the width direction The thickness D3c satisfies the following formula: D3e-D3c ≦ 1.0 μm, wherein the average film thickness D3e of the outermost region is the difference between the average film thickness of each of the outermost two regions and the average film thickness D3c of the central region. The average film thickness of the larger one. The extended laminated film according to any one of claims 3 to 5, wherein, when the extended laminated film is equally divided into nine regions in the width direction, the average film thickness D4e of the outermost region and the central region are The average film thickness D4c satisfies the following formula: D4e-D4c≦1.5 μm, wherein the average film thickness D4e of the outermost region is the average film thickness D4c of the average film thickness and the central region of each of the outermost two regions. The average film thickness of the larger difference. A polarizing laminate film comprising a polarizing layer film having a polarizer layer on at least one surface of an elongated base film, and an average film of the outermost region when the polarizer layer is equally divided into nine regions in the width direction The average film thickness D5c of the thickness D5e and the central region satisfies the following formula: D5e-D5c ≦ 0.25 μm, wherein the average film thickness D5e of the outermost region is set to be the middle and the average film thickness of each of the outermost two regions. The average film thickness of the region where the difference in average film thickness D5c is larger. The polarizing laminate film according to claim 7, wherein the average thickness of the polarizer layer in the width direction is 7 μm or less. The polarizing laminate film according to the seventh or eighth aspect of the invention, wherein, when the base film is equally divided into nine regions in the width direction, the average film thickness D6e of the outermost region and the average of the central region are obtained. The film thickness D6c satisfies the following formula: D6e-D6c≦1.0 μm, wherein the average film thickness D6e of the outermost region is the average film thickness D6c of the average film thickness of each of the outermost two regions. The average film thickness of the difference is larger. The polarizing laminated film according to any one of the items 7 to 9, wherein the polarizing laminated film is equally divided into nine regions in the width direction, and the average film thickness D7e of the outermost region is The average film thickness D7c of the central region satisfies the following formula: D7e-D7c≦1.5 μm, wherein the average film thickness D7e of the outermost region is set as the average of the average film thickness and the central region of each of the outermost two regions. The average film thickness of the difference in film thickness D7c is larger. The polarizing laminated film according to any one of claims 7 to 10, wherein the photometric correction unit transmittance Tye measured at a position 25 mm from the edge of the polarizing layer in the width direction is The photometric correction monomer transmittance Tyc measured in the center of the width direction of the polarizer layer satisfies the following formula: |Tye-Tyc|≦0.40% The photometric correction monomer transmittance Tye measured at a position of 25 mm from the edge is a photometric correction monomer having a larger difference between the two measured values and the photometric correction monomer transmittance Tyc measured at the center. Penetration rate. A method for producing a laminated film, comprising: applying an aqueous solution containing a polyvinyl alcohol-based resin to at least one surface of the elongated base film so that a central portion of the coating layer in the width direction is thicker than both end portions And a step of forming a coating layer; and drying the coating layer to form a resin layer containing a polyvinyl alcohol-based resin. A method for producing an extended laminated film, comprising the step of uniaxially stretching the laminated film according to claim 12 to more than 5 times to obtain an extended laminated film. A method for producing an extended laminated film reel, comprising the steps of: winding an extended laminated film according to claim 13 of the patent application into a roll to obtain an extended laminated film roll. A method for producing a polarizing laminated film, comprising: dyeing an extended laminated film according to claim 13 or an extended laminated film obtained by winding an extended laminated film roll according to claim 14 of the patent application; The step of polarizing the laminated film. A method for producing a polarizing plate, comprising: coating a protective film on a surface opposite to a side of a substrate film in a polarizing layer of a polarizing laminated film according to claim 15 of the invention; a laminating step; and a peeling step of peeling off the substrate film from the multilayer film.